Recently, a nitride light emitting device, a light emitting diode for acquiring light of a blue or green wavelength range, is fabricated with a semiconductor material having an empirical formula of AlxInyGa(1-x-y)N (here, 0≦x≦1, 0≦y≦1, 0≦x+y≦1). As such an LED has various advantages such as along life span, low power consumption, good initial driving characteristics, high vibration resistance, and the like, compared with a light emitting device based on a filament, demand for the LED continues to increase, and the recent active development of a high output LED promotes the use of the LED in diverse application fields such as an automobile light source, an electronic board, illumination, a light source for a backlight unit of a display, and the like.
In order to meet consumer demand, an LED package needs to have high luminance light emission characteristics. In general, the form of an LED package varies depending on an LED structure. First, when the LED has a structure in which a p-side electrode and an n-side electrode are formed on the same surface, the LED can be mounted on a sub-mount substrate through flip chip bonding. Thereafter, an underfill is performed to fill a resin member between the LED and the sub-mount substrate. Accordingly, the connection portion connecting the LED and the sub-mount substrate is protected by the resin member. The LED is then hermetically sealed with a silicon resin so as to be entirely covered. In the LED package having the flipchip structure, light generated from the LED is emitted in the opposite direction of the electrode surface. Until the light generated from the LED is discharged to an outer side, the light is reflected and diffused many times so as to be made incident on the surface of the sub-mount substrate. In this case, if the sub-mount substrate has low reflexibility, it absorbs the light, causing a loss of the light. Thus, it is preferable to employ a sub-mount substrate having high reflexibility. In this respect, however, in the case of a high output LED applying a high current in terms of the characteristics of an LED package, selection of a material having a high heat releasing characteristics and a material having a thermal expansion coefficient similar to that of the LED chip is a significant factor, so it may not be easy to select a substrate material having a high reflexibility. Also, a large amount of photons generated from the LED are absorbed and become extinct at the inner side of the underfill resin member. Namely, because light emitted from the LED is absorbed to become extinct by the underfill resin member surrounding the LED chip, it cannot easily come out of the LED package, degrading light output.
Meanwhile, as for different types of LED packages, in the case of an LED having a structure in which a p-side electrode and a n-side electrode are formed on the same surface, a growth substrate is die-bonded to a lead frame molded to a package main body so as to be mounted, and in the case of an LED having a structure in which a p-side electrode and an n-side electrode are formed on the opposite surfaces perpendicular to each other, a conductive substrate is die-bonded to a lead frame molded to a package main body so as to be mounted. Thereafter, the LED is hermetically sealed with a silicon resin so as to be entirely covered. In this type of LED package, until the light generated from the LED is discharged to an outer side after passing through the silicon resin, the light is reflected and diffused many times and made incident to the opaque conductive substrate, a die-bonding adhesive, the package main body, and the like, so as to be absorbed, causing a loss of light.
Thus, a package structure and method capable of preventing a loss of light caused as a light absorption due to a low reflexibility of the packaging material of the LED package are required.